Improved process and composition for tanning leather



aters e; z rr rnor NEW YORK, N.'Y., ASSIGNOR TO HIMSELF AND WERNERWERNER, or SAME PLACE. Latte rs Ma. No. 83,433, at; October 27, 1868.

' IMPROVED PROCESS AND COMPOSI'I'IQN FOR TANNING- LEATHER.

The Schedule referred to these Letters Patent and making part'of thesame.

To all whom 'it may comer-n:

Be it known that I, G. ZIPBE, of New York, in the county of New York,and State of New York, have invented a new and improved Process of andComposition for Tanning Leather; and I do hereby declare that thefollowing is a full, clear, and exact description thereof,.whichjwillenable-others skilled in the art to make and use the same.

This invention relates to a new tanning-composition, which is socompounded that the leather can be completely tanned in a few days,while heretofore it took months to do it.

My invention consists more. particularly in the use of a newcomposition, in which the leather is steeped, or, rather, with which itis impregnated; also, of a new soaping-compound for binding the metallicingredients of the former composition, and for making the leatherwater-tight.

The iuventiolralso consists of the process of treating the leatherduring. the tanning-operation.

The following is a description of the process and composition used I Theskins are, after the hair has been removed, first steeped in a solutionof sugar of lead, its strength being about 'i Baum, in which they remainabout twenty-four hours. They should be taken outevery now and then, tolet the liquid drop ofi, and then be steeped again. The skins havingthus been prepared for the impregnating-compound, are then steeped inthe same.

'This compound consists of about- Fifty parts of alcohol.

One hundred parts of water.

Seventy-two parts of sulphate of iron.

Sixteen parts of sulphm-ic acid.

Thirty-six parts of powdered manganese.

Twelve parts of sirup.

Twelve parts of common salt.

Three parts of chlorochromio acid.

I prepare the chlorochromio acid by fusing together in a tubulatedretort ten parts of chloride of sodium and sei' nteen palts ofbichromate of potassa, and dis-1 tilling tll'e anass with thirty partsof strong sulphuric acid.

Instead of thechlorochromic acid as prepared above, I also use an impureacid, prepared by simply heating together the chloride of sodium,bicln'omate of potash, and sulphuric acid, untildeconiposition takesplace.

Tocthis mixture is gradually added so much carbonate of soda as it cansustain without forming a .last-ing precipitate.

The sulphate -of iron is first dissolved .in boiling (water. This'mixture is well stirred with a wooden ladle, and then the sulphuricacid is added. This acid unites partly with the iron, forming sulphurousoxide of iron.

The manganese is then added, and completely con- .verts the..sulphurousoxide. into oxide of imn, also forming sulphate of manganese. One partof the oxide remains unbound in the solution, but will be absorbed, whenthe skins are inserted, by the acid contained in the leather, andliberated from the same.

The solution is then left standing for about thirty minutes, and thenthe chlorochromic acid is added.

The salt and sirup are also put in, while the compound is being wellstirred, and, finally, after the liquid has cooled down to about 99Fahrenheit, the alcohol is put in. p

The chlorochromic acid is only added to impart the requisite color tothe leather. It may therefore be omitted, if desired, or its quantity bediminished or increased at will. The more of it is taken, the lighterwill the leather become.

The application of the sugar-of-lead solution is not imperativelynecessary. It does, however, produce a' finer and denser leather, as itcauses sulphurous oxide of lead to be retained in the leather, wherebysuch leather is made more pliable and soft, which is par-- ticularlyimportant for thick being hammered.

The impregnating-composition can be made cheaper by leaving out thealcohol, and using water in its stead. The process of tanning wouldthereby,however, be extended, and the skins would, after tanning, haveto be thoroughly washed to remove all traces of the acid, while thealcohol transforms the acid into ether, and makes the washingunnecessary.

The addition of alcohol does consequently produce the quickest tanning,and it also forms, in connection with the sirup, a substitute for themanipulator, as the skins will, from the mixture, come out soft andsole-leather, to allow its.

. pliable.

The sirup forms, in connection with the acid, a brown, gelatinous,viscid substance, (humic acid,) which combines also with the metallicoxide, and which prevents the fibres from pasting together, andconsequently the leather from shrinking. The proportions aforementionedare intended for very thick leather, to bring the liquid to about 32 to33 Baum. For calf-skins, it requires 16, and for the thinner skins stillless. The thinner the leather, the more water is taken.

The thickest skins will require but little-more than sixteen hours to bethoroughly tanned; very thin skins, but a few minutes. At the edge thecompletion of the process can be readily ascertained.

The composition should have a temperature of about 99 Fahrenheit whenthe leather is steeped in it.

The skins are put into it, are well stirred therein, and frequentlytaken out and reinserted, until they are thoroughly impregnated with theliquid.

The skins are, atter having been impregnated, steeped in thesoaping-compoimd, which is composed of One part of linseed.

Sixty parts of tallow-soap.

Four parts of tallow.

Nine hundred parts of water.

Nine hundred parts of alcohol.

The skins are now completely tanned, soft, pliable, and strong.

The seeping-compound serves to insolubly bind the metallic contents ofthe impregnating-compound to the leather, and. also to make such leatherwaitertight For tanning kid gloves, it is also very useful, and asubstitute for the flour and yolk of eggs, heretofore used.

- The combinations which are produced in the skins during thetanning-process, and which, in the seepingeompound, are securely boundtherein, produce aleather more water-tight, more pliable, stronger, andmore duratble than it ever is in the ordinary well-known tanning\Vitnesses: I

Flume BLooKLnY, ALEX. .F. ROBERTS.

